Iodimetric determination of organo-aluminium compounds

Abstract

The alkyl groups in various types of organo-aluminium compounds have been shown to react with iodine in hydrocarbon solution, and the stoicheiometry has been determined of the reactions occurring between iodine and trialkylaluminium, dialkylaluminium chloride and dialkylaluminium alkoxide compounds.

Based on these reactions a reasonably rapid and accurate iodimetric method has been devised for the determination of low concentrations of organo-aluminium compounds in various hydrocarbon solvents. The method is applicable to the analysis of the hydrocarbon solutions of organoaluminium catalysts used for the polymerisation of ethylene and propene. Good agreement is obtained between the iodimetric procedure and by a procedure based on conductiometric titration with a standard solution of isoquinoline for trialkylaluminium compounds and dialkylaluminium chlorides. The iodimetric procedure is also applicable to dialkylaluminium alkoxide compounds, which cannot be determined by isoquinoline titration.